let previous = document.querySelector('.previous');
previous.addEventListener('click', function() {
	let items = document.querySelectorAll('.item');
	document.querySelector('.box').prepend(items[items.length - 1]);
});
let next = document.querySelector('.next');
next.addEventListener('click', function() {
	let items = document.querySelectorAll('.item');
	document.querySelector('.box').appendChild(items[0]);
});